360 



SCIENCE-GOSSIP. 



BRITISH FRESHWATER MITES. 



By Charles D. Soar, F.R.M.S. 



GENUS CUBVIPES KOENIKE. 



(Continued from page 330.) 



X. — Curvipes longicornis Koch. 

 Piersig says this mite is the same species as 

 0. nodatus. In this I must differ from him. The 

 colour is so divergent, and the adult size so small 

 when compared with C. nodatus, that I do not 

 think one can come to any other conclusion than 

 that they are two distinct species of the same 

 genus. The points of difference are constant in 

 several specimens that I have taken from different 

 localities. If the reader will refer to Koch's 

 great work (Deutschlands Crust., &c, heft 8, 

 figs. 11-12), Nesaea coccinea, which is synonymic 

 with C. nodatus, it will be seen what a beautifully 

 coloured mite is this, and that it exactly corre- 

 sponds in the colouring with our British speci- 

 mens of C. nodatus. Then, if reference is made to 

 heft 9, figs. 14-15 of the same work, which indi- 

 cate N. longicornis, a beautiful representation of 

 our British Curvipes longicorhis will be found. 



Female : Body. — Oval in form. Length about 

 1-20 mm. ; width, 0-92. Colour, a pale yellow, with 

 dark brown markings and a light yellow T-shaped 

 piece on the dorsal surface. Eyes rather large 

 and dark red. 



Legs. — First legs about l - 04 mm. ; fourth pair 

 about 1'60 mm. Colour, a pale yellow for the 

 first two or three joints, then gradually turning 

 into a pale blue towards the extremities. 



Epimera. — Arranged in much the same manner 

 as shown in (fig. 2) C. nodatus. 



Palpi. — About - 50 mm. in length, and the 

 same as shown at fig. 5, in shape. I cannot find 

 any difference in the structure of this mite and 

 that of C. nodatus, but the difference in the size 

 and colour is so marked and so constant that I feel 

 strengthened in my opinion in regarding this as 

 a distinct species. 



Genital Plates. — These have two discs much 

 larger than the others (fig. 6) and numerous 

 small ones, which vary in ntunber, but each plate 

 has about twenty discs. 



Male. — About 0'90 in length. Colouring is the 

 same as that of the female, with the difference 

 that the male has a red T-shaped piece on the 

 dorsal surface, whilst it is yellow in the female. 

 I should not like to say that this is constant ; but 

 Koch, in his drawing, shows the same distinction. 

 I have only taken four males of this species, but 

 the colouring is the same in all cases. The palpi 

 of the male are 0'48 mm. in length. 



XL — Curvipes circularis Piersig. 

 Body. — A broad oval. Length about 1'40 mm. 

 Width about 1 - 18 mm. Colour, yellow, with 



darker yellow and brown markings on the dorsal 

 surface. Fig. 37 shows the ventral area. 



Legs. — A darker yellow than the body and 

 inclined to red. First legs, about 1*20 mm. in 

 length. The fourth legs are about 1*50 mm. 



Epimera. — Very small (fig. 37) in comparison 

 with the surface of the body. 



Palpi. — About 0-50 mm. in length. There is 



Fig. 37, C. circularis. — Female, ventral surface, 

 a difference, as is usual, in this part. The spines 

 on the second and third joints are plumose. 

 Fig. 38 is drawn from the inner side of the right 

 palpus. There are three small pegs in a row, 

 visible on that side of the palpi. 



Genital Plates are also different from the 

 previous species of Curvipes. They are quite 



Fig. 38, C. circularis. — Inside surface of right palpus, 

 different from fig. 32, in having the anterior disc 

 on a small plate (fig. 25) by itself. The form of 

 the genital plates in Curvipes rufus is much nearer 

 to that of this species, but the plates are of quite 

 a different shape ; the plates in C. circularis being 

 sickle-shaped. 



Localities. — This mite is not common. I have 

 not seen more than five specimens ; I have not yet 

 found a male specimen of this species. 



I have not adopted any particular scale for the 

 figures in these articles, but have drawn them in 



